Heat exchangers are used extensively in manufacturing plants for various applications. For example, as described in U.S. Pat. No. 6,681,839 to Balzer, heat exchangers may be used to maintain process control over various manufacturing processes such as in the production of plastics and other chemicals. These heat exchangers include exchange-tubes through which the manufactured chemicals must flow that often become narrowed by the accumulation of the chemicals on the inner walls of the exchange-tubes. This narrowing causes inefficient heat exchange and can reduce plant production.
To alleviate this narrowing build up, a work crew must typically partially disassemble the plant in order to move the heat exchanger to a location where another work crew can then manually position a high pressure cleaning lance through each of the exchange-tubes to remove the narrowing build up. Cleaning the exchange-tubes manually with a high pressure cleaning lance is dangerous to the workers because the cleaning lance generates high pressure jets of water that can injure a worker. Also, the narrowing buildup removed by the high pressure jets can include dangerous chemicals that can poison and/or chemically burn the skin, lungs, eyes and other body parts of the workers on the work crew. In addition, manual cleaning of the exchange-tubes with a high pressure cleaning lance is slow, physically exhausting and expensive to perform.
An example of a rigid lance machine is available from Stoneage, Inc. of Durango, Colo. The Stoneage lance machine includes a pair of parallel slide rails that guide a plurality of polymeric guide supports. The rigid lance, of roughly a quarter inch diameter, rides through a hole in the guide supports, each of which is about an inch thick. The lance is coupled to a prime mover, which rotates the lance at a high speed as the lance is fed into an exchange-tube of a heat exchanger. As the prime mover is moved forward in order to advance the lance into the tube, each sequential guide support comes into abutting contact with the guide support in front of it. Thus, the guide supports stack up as the lance moves into the tube. For this reason, the machine is limited in the number of guide supports that can be used, yet the guide supports must be close enough together to prevent the lance from buckling as it rotates. This severely limits the machine because if, for example, fifty such guide supports are mounted on the machine, then the prime mover can get no closer than 50 inches away from the entry into the tube bundle.
Thus, there remains a need for heat exchanger tube lancing machine that is not so limited, allowing the prime mover to move as close as possible to the entry into the tube bundle, while still providing superior cleaning capability of the lancing machine. The present invention is directed solving these and other needs in the art.